def test_change_d():
"""
testing changing the diameter
"""
c = Circle(4)
c.diameter = 4
assert c.radius == 2
assert c.diameter == 4
assert round(c.area, 5) == 12.56637
def test_change_r():
"""
testing changing the radius
"""
c = Circle(4)
#"setting the radius to 2:"
c.radius = 2
assert c.radius == 2
assert c.diameter == 4
assert round(c.area, 5) == 12.56637
def test_from_diameter():
c = Circle.from_diameter(6.0)
assert c.radius == 3.0
def test_set_area():
# trying to set the area
c = Circle(4)
with pytest.raises(AttributeError):
c.area = 12
